Many different forms of implantable medical devices are known for treating a wide variety of medical conditions. Examples of such devices include vena cava filters and occlusion devices, which are advantageously implanted into a patient by an endoluminal delivery procedure from a remote access point up to the treatment site. It is important for such devices to be able to be located precisely in the vessel with good patency to the vessel wall, that is to fit closely against the vessel wall so as to minimise, preferably avoid, leakage around the device. It is also important for such devices to be stable over time, particularly to exhibit minimal risk of migration and minimal loss of orientation in the vessel. Such devices should also seek to minimise damage to the vessel wall so as to seek to avoid trauma to the vessel, which can cause stenosis and other adverse effects.
In general terms there are two kinds of occlusion devices. A first kind generates instant occlusion of a vessel by a mechanical closure of the device. The other kind of vascular occlusion device relies upon the generation of a thrombus at the occlusion device to close off any residual passage through the device. This latter form of vascular occlusion device typically slows the flow of blood in the vessel, which causes clotting at the location of the device and as a consequence the formation of an occluding barrier. Instant mechanical occluders, while being preferable for many medical indications, can involve less than optimal delivery procedures, particularly given that many conventional occluders of this nature are not suitable for delivery over a guide wire. Some devices which are modified to be able to be delivered over a guide wire require additional steps during the deployment process, additional components and/or have relatively poorer delivery characteristics such as poor radial compressibility and flexibility when in the delivery configuration. Some occlusion devices also suffer from the risk of recanalization of the vessel over time.
Similar considerations apply to filters and other similar implantable medical devices.
Some examples of implantable medical devices are described in US-2010/0163054, U.S. Pat. No. 6,254,633, US-2006/0058820 and US-2003/0153935.